Telephone system



Nov. 4, 1941. R. E. HERsEY F:rA|

TELEPHONE SYSTEM Nov. 4, 1941. R. E. HERsEY r-:TAL

TELEPHONE SYSTEM Filed May 15, 1940 9 Sheets-Sheet 2 *mis* /NVENTO/QS: O MyERs J. 8. NEWSOH Nov. 4, 1941. R E HERSEY ETAL 2,261,370

TELEPHONE SYSTEM Filed May l5, 1940 9 Sheets-Sheet 3 MA RK E R E/ao5 V MA Rl( E l? CONNECTOR Rfwmsfr VVE/vrom,V 33320;;

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TELEPHONE SYSTEM Filed May 15, 1940 9 Sheets-Sheet 4 ATTORNEY Nov. 4, 1941. R. E. HERsEY ETAL 2,261,370

TELEPHONE SYSTEM Filed May l5, 1940 9 Sheets-Sheet 5 llli rlrn A TTORNE V Nov. 4, 1941.

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TELEPHONE SYSTEM Filed May 15, 1940 9y sheets-sheet e Aff-mir /N VEN TORS OIM'YERS J. B. NEWSOM ATTORNEY NOV. 4, 1941. R, E, HERSEY ETAL 2,261,370

TELEPHONE SYSTEM Filed May l5,

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'TELERHONE 'SYSTEM Filed lMay l5, 1940 9 Sheets-Sheet 8 Ill-Ils o HJroPR /NVEA/roRs. O'WERS By J. B. NE WS 0M Afro/Wgr 9 Sheets-Sheet 9 ,mln-WTS [hD-l TELEPHONE SYSTEM Filed May 15,

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Patented Nov. 4, 1941 TELEPHONE SYSTEM Ralph E. Hersey, Madison, N. J., and Ottmar H. Kopp, Baldwin, Oscar Myers, Mount Vernon, and James B. Newsom, Great Neck, N. Y., assignors to Bell Telephone Laboratories, Incorporated, New York, N. Y., a corporation of New York Application May 15, 1940, serial No. 335,241

(c1. 17a-1s) 10 Claims.

This invention relates to telephone exchange systems and more particularly to systems of the so-called cross-bar type for enabling the terminating equipment to be used in common for terminating calls in two oiiices serving a maximum of twenty thousand directory numbers.

In telephone exchange systems the exchange areas, are for convenience in establishing connections, divided into a plurality of offices each serving ten thousand subscribers lines. Each of the oiiices is provided with switching equipment for establishing connections from subscribers lines terminating therein to other lines which may terminate in the sameor another office and is provided with originating sender and marker equipment for controlling a portion of the switching equipment on calls originating in the office and with terminating sender and marker equipment for controlling a further portion of the switching equipment to terminate calls incoming to the oce. In some instances two oices may be located in the same oiiice building and a considerable saving in equipment could be realized if the terminating equipment could be used in common for both offices.

It is therefore an object of the present invention to decrease the cost of equipping two oiices which are located in the same building by combining the terminating equipment of the two olices in such a manner that both oices are served by the same terminating senders and markers and in some cases by the same incoming trunks, incoming frames and line-link frames.

In accordance with the present invention, the trunks incoming to such common terminating equipment serving two oiiice units may be rarranged in a common group selectable at an originating oice in response to the dialing of the oflice code digits of either of the terminating office units or may, as an alternative, be in separate groups selected in response to the dialing of the respective oiiice codes of the units, In either case, the seizure of an incoming trunk is effective to cause the seizure of an idle terminating sender at the combined terminating office through a sender link and, after the numerical digits have been registered in the terminating sender, to

Vcause the association of an idle marker with such marker information for terminating the connection in the proper omce unit.

If a common group of incoming trunks is used, it is necessary to supply this information from the originating sender. This is accomplished during the transmission of revertive impulses from the terminating sender to the originating sender, which impulses cause the transfer of the numerical portion of the wanted line directory .number to the registering equipment of the terminating sender and particularly during the transmission of impulses from the terminating sender which satisfy the incoming group registration in the originating sender. yThe originating sender is modified so that when the common group of trunks has been selected in accordance with the operation of the route relay of the originating marker in response to the dialing of the office code of one of the two office units, for example ofce A, the counting relays of the originating sender will satisfy the incoming group register of the sender after one to four revertive impulses have been received and that when the common group of trunks has been selected in accordance with the operation of the route relay of the originating marker in response to the dialing of the ofce code of the other of the two office units, for example of ofice B, the counting relays will satisfy the incoming group register only after from six to nine revertive impulses have been received. Since the number of revertive impulses transmitted from the terminating sender is recorded on the incoming group vertical of the cross-bar register thereof, this affords a means for informing the terminating sender as to the office unit destination of a call. This information is passed to the terminating marker over a special conductor extending through the marker connector to control a transfer relay in the marker, this relay being unoperated if the connection is to be terminated in office A and operated if the connection is to be terminated in office B. This relay is instrumental in connecting the marker to either one of the two number group frames allocated to the two oice units so that from the selected number frame, the marker will receive the necessary information for controlling the incoming and line-link frames used commonly for both offices to select the desired line in the proper office unit. y

If separate groups of incoming trunks are used, the previously indicated modication of the originating sender is not necessary since the group of incoming trunks seized identifies the destination 55 of the call in either the A or B oice units and this identification is passed over the terminating sender link circuit to the terminating sender and thence to the marker to operate the transfer relay above mentioned.

For a more comprehensive understanding of the invention, reference may be had to the following detailed description taken in connection with the accompanying drawings, in which:

Fig. 1 shows schematically the arrangement of equipment embodying the present invention;

Fig. 2 shows schematically subscribers lines terminating in an originating oilce, line-link, district and ofiice frames of cross-bar switches for extending connections from such lines, a sender link and control circuit for extending a connection from any district junctor to an idle sender and district and oice frame connectors for associating the district and office frames with a marker;

Fig. 3 shows such portions of an originating sender, marker connector and marker as are necessary to an understanding of the invention;

Figs. 4 to 9, inclusive, disclose such portions of the equipment of the terminating office as are necessary to an understanding of the invention; Fig. 4 showing schematically a plurality of incoming junctors, an incoming link and connector for associating any incoming junctor with an idle terminating sender, and relay equipment for transmitting an identification of the group of incoming trunks seized for the completion oi a connection to the terminating sender; Fig. 5 showing such portions of the terminating sender as are of particular interest in connection with the present invention and a marker connector by which an idle terminating marker is associated with the sender; Fig. 6 showing a portion of the terminating marker embodying the invention; Fig. 7 disclosing an incoming frame and one number group of each of the two office units served in common by the terminating sender and terminating marker; Fig. 8 showing additional relays and circuits of the terminating marker of Fig. 6 and Fig. 9 showing a plurality of line-link frames in each of two line choices and subscribers lines terminating, respectively, in two office units; and

Fig. 10 is a chart indicating how the several figures of the drawing should be arranged to completely disclose the invention.

Referring iirst to Fig. 1, the operation of the system is briefly as follows: Upon the initiation of a call, for example on the subscribers line 200, the line is extended by the primary and secondary line switches such as 20l and 202 of the line-link frame to an idle district junctor 203 and through the primary and secondary sender link switches 204 and 205 on the sender link and control frame to an idle originating sender 300. When the subscriber dials the wanted line designation, the digits of that designation are registered in the sender, an idle marker 302 is attached to the sender by the marker connector 30| and the marker in turn connects by means of a district frame connector 2|3 with the vdistrict link on the district frame in which the district junctor 203 appears. By means of an oilice frame connector 2I4, the marker selects and connects with an ofiice link having access to an idletrunk extending to the wanted omce. The marker then controls the establishment of the connection from the district junctor 203 to the idle outgoing trunk over primary and secondary switches such as 209 and 2l0 on the the line number registered in the marker.

district frame and over primary and secondary switches such as 2li and M2 on the ofilce frame.

Upon the seizure ot an idle trunk, such as 25. terminating in an incoming junctor 400 at the terminating oiilce, assumed to serve two office units A and B, the incoming junctor becomes associated through the primary and secondary switches 404 and 405 of the terminating sender link frame with an idle terminating sender such as 500. Upon its seizure, the sender proceeds to transmit series of revertive impulses back over the established connection to the originating sender 300 to satisfy the originating sender with respect to the setting of its register which was set in response to dialing to register the numerical digits of the wanted line number. These impulses at the same time cause the setting of the cross-bar register of the terminating sender 500 to register the numerical digits of the called line designation for controlling the completion of the connection. The seizure of the terminating sender also causes the association of an idle terminating marker such as 600 therewith over the marker connector 50|.

If it is assumed that both terminating ofiice units A and B may be reached over the same group of incoming trunks including trunks 2|5 and 2I8, inclusive, the originating sender 300 will be arranged in such a manner that with a route relay of the originating marker 302 operated in accordance with the office code of the terminating office unit A, it will be satisfied during the transmission of the incoming group series of impulses after from one to four revertive impulses have been received, but that with a route relay of the originating marker operated in accordance with the oiice code of the terminating oflce unit B, it will be satisfied during the transmission of the incoming group series of impulses after from six to nine revertive impulses have been received. Accordingly, the cross-bar register of the terminating sender 500 will, due to its setting, determine in which office unit the call should be terminated and will transmit this information to the associated terminating marker to operate a transfer relay therein. If it be assumed that each terminating ofiice unit may be reached over a separate group of incoming trunks. for example that oilice unit A may be reached over the group including trunks 2l5 and 2 l'l and that ofilce unit B may be reached over the group including trunks 2I6 and 248, then the originating sender 300 will not be arranged as just described but information with respect to the desired oflice unit will be transmitted to the terminating sender 500 in accordance with the incoming frame on which the selected group of incoming trunks terminate and this infomation will then be transmitted to the terminating marker to operate the transfer relay thereof.

With the information required for controlling the termination of the connection transferred to the terminating marker, the marker rst selects the number group frame |40 or 190 of the A or B terminating oice in accordance with the unoperated or operated condition of its transfer relay by the operation of either the number group frame connector 104 or 154 and then selects the portion of the selected number frame in which the wanted line terminates in accordance with The number group frame then transmits information to the marker to inform the marker with respect t th li'n choice Ain which the wanted line terminates, the frame within the choice and the level on the frame and other information as to whether the wanted line is an individual line, a party line or one of a group of lines leading to a private branch exchange, and if the line is a party line Whether the tip or ring substation on the line is desired. In accordance with this infomation the marker then proceeds to associate itself over an incoming frame connector 103 and a line-link frame connector 923 with the incoming frame in which the calling junctor terminates and with the proper line-link frame in which the wanted line terminates and to control the completion of the connection from the calling incoming junctor over the primary and secondary switches 100 and 10| of the incoming frame and over the primary and secondary .switches 900 and 90| of the proper line-link frame to the wanted line, for example, to line 930 in oiiice unit A or to line 980 in oice'unit B.

rI'he circuits of the originating and terminating ofdces are in general similar to those fully disclosed and described in Patent 2,089,921, granted August 10, 1937 to W. W. Carpenter, the circuits of the terminating oiiice being, however, modified in accordance with the circuits disclosed in the Patent No. 2,232,371 granted Feb. 18, 1941, to J. W. Dehn and O. Myers, but the circuits of both the originating and terminating oices have been further modified to embody the present invention.

It will rst be asfumed that a call is initiated on calling line 208 and that the calling subscriber desires a connection to line 930 terminating in office unit A of the combined terminating oce. Upon the initiation of the call the calling line is connected to an idle district junctor such as 203 over an idle link such as 2|9 on the linelink frame by the'operation of the primary line switch 20| and the secondary line switch 202 and the district junctor 203 is connected to an idle sender 300, portions of which are schematically disclosed in Fig. 3, by the operation of a primary switch 204 and a secondary switch 205 on the sender link and control frame. As soon as the calling line has been extended to the idle sender, the calling subscriber receives the usual dial tone and proceeds to dial the digits of the oice frames are operated to complete the cirrectory number of the wanted line 930 whereupon these digits are registered on the cross-bar register equipment of the sender. In order to simplify the disclosure, only such portions of the thousands vertical 303 and of the hundreds vertical 304 of the cross-bar register of the sender are disclosed as are necessary to illustrate the present4 invention.

Following the registration of the dialed code digits on the cross-bar register of the sender, an idle originating marker 302 is associated with the sender through the operation of the usual marker connector 30| and the oiiice code digits are transferred to the incoming registers of the marker in the welt-known manner resulting in the operation of a route relay in the marker. It will be assumed that since the oiiice code dialed and registered in the marker indicates that the call is to be extended to line 930 terminating in the ofl'lce unit A of the combined terminating oflice, route relay 305 is therefore operated. Un der the-control of the operated route relay, the marker now proceeds to associate itself over the district frame connector 2|3 with the district frame into which the calling district junctor 203 is incoming and to associate itself ovir the office frame connector 2|4 with the oflice frame in which the group of trunks extending to the wanted terminating oilice terminates. The marker then proceeds to test for idle links on the district frame to which the calling district junctor 203 has access, to test for idle oice trunks, to

test for idle links on the ofce frame and to test for idle outgoing trunks in the group extending to the desired terminating ofllce. When such tests have been completed and it has been determined that a circuit path is available from the district junctor to an idle outgoing trunk, primary and secondary switches on the district and oflice frames are operated to complete the circuit path. For example, this circuit path may be extended from the district junctor 203 over the primary switch 209, link 206, and secondary switch 2|0 on the district frame, office trunk 201 over the primary switch 2|I, link 208 and secondary switch 2|2 on the oftice'frame to the outgoing trunk 2|5.

It will be rst assumed that lines terminating either the A or B oiilce units may be reached over the same group of lnterofiice trunks, that is over any trunk of the group including trunks 2|5 to 2|8, inclusive, which terminate at the terminating oiiice in the incoming junctors 400 to 403. Trunk 2 l5 having been selected as previously described, the incoming junctor 400 functions to associate itself with an idle terminating sender 500, portions of which are disclosed i-n Fig. 5, over a primary switch 404 and a secondary switch 405 of the incoming link and sender connector frame in the well-known manner. In part, this is accomplished by the operation of a group start relay 401, common to a group of incoming junctors such as the group including junctors 400 and 40|, over a back contact of relay 406, relay 401 in turn causing the operation of a trunk group relay 408 for the trunk groupin which the calling trunk 2|5 is located. A test is then made for an idle sender and subgroup relay 409 of a subgroup of terminating senders, in which an idle sender is located, is operated followed by relay 502 individual to the idle sender. The primary and secondary switches 404 and 405 of the sender connector frame are then operated to connect the calling junctor 400 with the selected idle sender.

Under the assumption that both oce units may be reached over a common trunk group represented by the operated trunk group relay 408, the front contacts of relay 408 will both be connected to ground. The upper armature of relay 408 will be connected over conductor 4I0, the

` upper contact of relay 409 and conductor 4|2 to conductor 503 or over conductor 4| the next to upper contact of relay 409 and conductor 4|3 to conductor 504 dependent upon whether the number of the incoming frame in which the trunk group terminates is under or over ten and the lower armature of relay 408 will be connected over conductor 4|5, the inner contact of relay 409 to conductor 506. Thus with relay 502 of the terminating sender 500 operated, either relay 501 or 508 will be operated over conductor 503 or conductor 504 to indicate to the sender whether the number of the incoming frame is under or over ten and relay 509 will be operated over conductor 506 to indicate to the sender that a trunk of a group common to two oiiice units has been seized. 'I'hese relays, if operated, lock under the control of off-normal relay 5|| which operated when the sender was seized.

Both relays S01 and 503 and both relays 509 and I0 should not be simultaneously operated and therefore with relay 509 operated and either relay 501 or 508 operated, a circuit lis established for relay 5I2 extending from battery through the winding of relay 5I2, upper front contact of relay 509, back contact of relay 5I0, back con-l tact of either relay 501 or 503 dependent upon which is unoperated, thence to ground. Relay 5I2 operates, locks under the control of relay 5I I and conditions the sender for operation. As fully disclosed in Patent 2,089,921 to Carpenter, hereinbefore referred to, the terminating sender proceeds to register the incoming frame infomation transmitted from the incoming link, a portion of which has been indicated by the operated condition of either relay 501 or 500 and to transmit series of revertive impulses to the originating sender 300 of Fig. 3 to satisfy the sender with respect to the setting of the numerical digit portion of its cross-bar register. The circuit over which these impulses are transmitted extends from the terminating sender 500 over the tip and ring fundamental circuit conductors extending over contacts of switches 204, 205, 209, 2I0, 2li, 2I2, 404 and 405, the tip conductor 220 of fundamental circuit at the originating sender 300 being looped to the ring conductor 22| over a normal contact of relay 301, a front contact of relay 308, a back contact of relay 300 through the windings of overflow relay 3I0 and stepping relay 3II, a back contact of relay 3I2 and a front contact of relay 3I5. Stepping relay 3II operates in response to each impulse transmitted in each series of revertive impulses.

It has been assumed that the calling subscriber dialed the directory number of subscribers line 930 terminating in oftlce A and that route relay 305 of the originating marker 302 has been operated. Under this condition, relay 303 is operated and therefore when the terminating sender 500 transmits the incoming group series of impulses to satisfy the incoming group setting of the register of sender 300 as determined jointly by the thousands and hundreds digits registered on the thousands vertical 303 and the hundreds vertical 304 of the register, the fundamental circuit will be opened by the operation of relay 3I2 after from one to four impulses have been received and counted by the counting relays of the sender. If it be assumed that the thousands digit registered was 0 and the hundreds digit was 4 and that, therefore, register cross-points 3I6 and 3I1 are closed, then on the iirst operation of stepping relay 3H in response to the first impulse of the incoming group series, with steering relays 3I8 and 3I9 operated, a circuit is established from ground over the upper back contact of relay 320, contacts of stepping relay 3II, lower back contact of relay 320, front contact of relay 32|, back contact of counting relay 333, back contact of counting relay 323, contact of relay 3| 9, crosspoint contacts 3I1, the left cross-point contacts 3I5, front contact of relay 3I5, front contact of relay 3I8, front contact of relay 306, winding of counting relay 3I3 to battery. Relay 3I3 operates and locks in series with counting relays SI2 and 3I4 and over its own front contact to ground at the right front contact of relay 308, but relays 3I2 and 3I4 do not operate in this locking circuit since their windings are shunted so long as stepping relay 3II remains operated. When relay 3II releases, however, relays 3I2 and 3I4 operate. Relay 3I2 upon operating opens the fundamental circuit to terminate the impulse aneraro series and prepares the circuits ofthe sender 300 for controlling the setting of the register of the terminating sender in accordance with the setting of its register for iinal brush selection. Since the originating sender was satisfied after the receipt of one revertive impulse in the incoming group series, the terminating sender 500 has functioned to close cross-point contacts 5I3 of the incoming group vertical of its cross-bar register in the manner fully set forth in the patent to Carpenter above referrc, to.

Had the calling subscriber dialed the directory number of subscribers line 980, terminating in ofce unit B, route relay 334 would have been operated in accordance with the oiiice code digits dialed. In this case, relay 305 would not be operated and assuming that the numerical digits dialed were the same as dialed to reach the subscribers line 930, cross-point contacts 3I6 of the thousands vertical 303 and cross-point contacts 3 I 1 of the hundreds vertical would be closed. When now the terminating sender 500 transmits revertive impulses to cause the selection of a set of cross-point contacts in its incoming group vertical, as determined by the joint closure of cross-point contacts 3I3 and 3I1 of the originating sender, relay 3H upon operating in response to the first impulse closes a circuit from ground at the upper back contact of relay 320, contacts of relay 3H, lower back contact of relay 320, front contact of relay 32|, back contact of counting relay 333, back contact of counting relay 323, contact of steering relay 3I9, cross-point contacts 3I1, left cross-point contacts 3I6, right contact of relay 3I5, contact of steering relay 3|8, back contact of relay 306, winding of counting relay 332 to battery. Relay 332 operates and locks through the winding of counting relay 333 and over its own front contact to ground at the front contact of relay 308, but relay 333 does not operate in this locking circuit since its winding is shunted so long as relay 3II remains operated. As soon as the first revertive impulse ceases, relay 3I I releases and counting relay 333 thereupon operates.

When relay 3II operates in response to the second revertive impulse, the circuit controlled thereby is extended over the front contact of counting relay 333 and the back contact of counting relay 33| to battery through the winding of counting relay 330. Relay 330 thereupon operates and locks through the winding of relay 33| and its own front contact to ground at the right back contact of relay 303, but relay 33| does not operate in this locking circuit until relay 3| I releases at the end of the second revertive impulse. In a similar manner in response to the next three revertive impulses, counting relays 328, 329, 326, 321, 324 and 325 operate and lock. When relay 3II again operates in response to the sixth revertive impulse, with counting relay 325 operated, a circuit is established over the front contact of relay 325, the back contact of relay 335, to battery through the winding of counting relay 3I3 which thereupon operates and locks in series with relays 3I2 and 3I4. When relay 3II releases upon the termination of this impulse, counting relays 3I2 and 3I4 operate in the locking circuit of relay 3I3, relay 3I2 functioning to terminate the transmission of further impulses in the incoming group series and relay 3I4 functioning to prepare the sender 300 for receiving impulses of the final brush series. Since the sender 300 was satised after the receipt of six revertive impulses in the incoming group series, the terminating sender 500 has functioned to close the cross-point contacts |4 of the incoming group vertical of its crossbar register. It will thus be seen that for a call to a line terminating in oiilce unit B, the originating sender has required the terminating sender to transmit five additional impulses in the incoming group series and therefore while the closure of cross-point contacts 5|3 or 6|4 at the terminating sender will register the same incoming' group information, the closure of cross-point contacts 5|8 will indicate that a line terminating in oillce unit A is desired whereas the closure of cross-point contacts 5|4 will indicate that a line in onlce unit B is desired.

When the remainder of the information concerning the numerical identification of the wanted line has been transferred from the originating 'sender 300 and registered in the terminating sender 500. a signal is transmitted to the originating sender 900 to cause its release and the terminating sender is associated with an idle terminating marker over the marker connector It will be assumed that the marker 600, such portions of which as are essential to an understanding of the invention being disclosed in Figs. 6 and 8, is available and becomes connected with the sender 500. Following the connection of the marker with the sender, a circuit is established for signaling the marker as to whether the wanted line terminates in ofllce unit A or oillce unit B served by that marker. If, as assumed, both oiiice units are reached over a common group of trunks and relay 509 has been operated as previously described, then if the cross-point contacts 5|3 of the incoming group vertical of sender 500 have been closed indicating a call for a line terminating in oillce unit A, a circuit is established from battery through the winding of relay conductor 602, contacts of marker connector 50|, lower contacts of relay 509, cross-point contacts 5|3, to the checking lead 5|5 but relay 60| does not operate over this circuit and consequently relay 603 is operable over the back contact of relay 60|. Had the cross-point contacts 5|4 been closed, then the circuit just traced for relay 60| would have been completed over conductor 5|6 to ground and relay 60| would have operated to cause the operation of relay 604 over its front contact. It is to be noted that if the sender 500 is allocated to serve trunk groups over which two ofiice units may be reached, the arrow connections indicated a't the cross-point contacts of the incoming group register of sender 500 would be united.

Upon the association of the sender with the marker, a plurality of other control circuits are established over which the digits of the registered wanted line designation are transferred from the sender to the marker and recorded on groups of register relays represented by thousands relay 605, hundreds relay 606, tens relay 601, and units relay 608. The hundreds relay 606 indicates Whether the hundreds digit is greater or less than 5 by operating relay 609 for digits greater than 5 and indicates the position of the digit in either series by operating one of ilve relays such as relay 6|0. The thousands relay 605 marks one of ten conductors, such as conductor 6H, which is extended to either relay 6|2 or 6|3 according as relay 609 is or is not operated to either relay 6|4 or 6|5 according as relay 609 is or is not operated and relay 604 is operated. Therefore, the joint operation of the thousands and hundreds register relays identifies one of forty groups of iive hundred lines each by operating one of a set of twenty relays'such as 6|2 and 6|3 allocated for calls to oillce unit A or by operating one ofa set of twenty relays such as 6|4 and 6|5 allocated for calls to office unit B dependent upon whether relay 608 or relay 604 is operated.

'I'he tens register represented by relay 601 discriminates between even and odd digits by operating relay 6|6 for odd digits and identifies blocks of twenty numbers by operating one o! a set of five relays such as 6|1 which in turn operate relays such as 6|8. The units register relay 608 grounds one of ten conductors which are extended to twenty conductors according to the operated or non-operated condition of relay 6|6.

The joint operation of relay 6|0 and either relay 6|2 or 6|3 selects a number group frame in the ofilce unit A by completing a circuit for a marker preference relay such as or 106. Similarly, the joint operation oi' relay 6|0 and relay 6|4 or 6|5 selects a. number group frame in the oilice unit B by completing a circuit for a marker preference relay such as or 156. In each number group connector, there is a marker preference relay for each marker and these preference relays are arranged in a chain circuit so that only one marker can attach itself to a number group frame at a time. It will be assumed that the wanted number terminals are on number group frame 101 allocated to the oillce unit A and that preference relay 105 is operated as soon as-the frame is idle, in turn operating a multicontact relay 108 which closes the necessary circuits between the marker and the number group frame. With relay 108 operated, the hundred block relay 109 is operated under the control of relays 6|0 and 6|3, there being one relay 109 for each one hundred numbers included in the number group. With relay 109 operated, twenty block relay 1|0 is operated under the control of relays 6|8 and 109, there being oneb such relay for each twenty numbers in -the number group `frame.

With relays 108, 109 and 1|0 operated, twenty sets of three terminals each on the number frame 101, such as 1|| to 1|3, and 1|4 to 1|6 are marked by connecting them to equipment in the marker. For example, terminal 1| I is connected over front contacts of relays 1 |0 and 108 and the back contacts of relay 6|9 to the Winding of busy test relay 62|, while terminal 1| 4 is similarly connected over a back contact of relay 620 to the winding of busy test relay 622. The corresponding terminals on the other eighteen sets are also connected to intermediate relays in the set of twenty busy test relays. Terminals 1|2 and 1|5 are connected to armatures of selecting relays 6|9 and 620 respectively and the corresponding terminals of the remaining sets are connected to armatures of intermediate'relays of this group and terminals 1|3 and 1|6 are connected over back contacts of relays 6|9 and 620 to the windings of relays 623 and 624 which become effective only in the case of terminal hunting groups.

In order to connect with a wanted line it is necessary to select the choice, the frame and the level of the frame on which the line is located and also to determine the class of service to which the line is entitled. Therefore there is provided in the marker a group of line choice relays 600, 80|, etc., there being one for each choice. Since each choice includes four frames with ten levels on each frame, a set of twenty double wound relays 802 to 805 is provided each pair of relays 802 and 803 or 804 and 805 representing one of the ten levels and each relay representing a pair of frames, the two windings of each relay distinguishing between frames of the pair. In order to differentiate between the three types of service, the line choice relays 800, 80|, etc., have three windings each and are energized over the different windings in accordance with the type of service to which the line is entitled. Therefore, there is a maximum of thirty conductors leading from the line choice relays and a maximum of forty conductors outgoing from the frame or level relays. These conductors are extended in multiple to all of the number frame connector relays such as 108, 13|, 158 and 18| and over contacts oi these relays to sets of terminal strips of the number group frames. The operating conductors 806, 801 and 608 for relay 800 extend to terminal strips 1|1, 1|8 and 1|9 and similarly the operating conductors 809 to 8|2 for the frame level relays 802 and 803 are connected over contacts of relay 108 to terminal strips 120 to 123, it being assumedthat connector relay 108 is operated.

The subscribers line 930 oi' oiiice unit A where it enters the oiilce is connected to a distributing frame 903 from which the line is extended to one of the primary line switches 90| in accordance with the traflic requirements.A The line itself is connected to the line terminals 904 and 905 while individual to the line terminals 904 and 905 are the sleeve or busy terminal 906 and the message register terminal 901.

At the number frame, assuming that the set of number terminals 1| l, 1| 2 and 1|3 represent the number assigned to line 930, terminal 1|| will be cross-connected over jumper 124 to terminal 905 individual to the position in the primary switch 90| assigned to the line 930. According to the present disclosure, line 930 appears in the No. 0 level of the No. 0 frame in the No. 0 choice and is an individual message rate line. Therefore, terminal 1|2 is connected over jumper 125 to strip 120 and terminal H3 is connected over jumper 126 to strip 1|1.

When the twenty block relay 1|0 operates as above described, the sleeve test circuit for line 930 extends from battery through the winding of relay 62|, back contact of relay 6|9 over iront contacts of relays 108 and 1|0, terminal 1||, jumper 124, to the sleeve terminal 906 individual to the line. If the line is busy relay 62| operates from the busy ground on the sleeve of the line. At the same time battery through the winding of relay 623 is connected over the back contact of relay 6|9, over contacts of relays 108 and 1|0, terminal 1|3, thence over jumper 126, strip 1|1, 'conductor 806. left winding of the No. 0 line choice relay 800 to battery. Therefore relay 623 does not operate. After an interval to permit the busy test relays 62|, 622, etc., to opcrate. ground is connected under the control of the units register to conductor 625 thereby operating relay 6|9 provided relay 62| is not op, erated. With relay 6|9 operated, ground is connected to conductors 626 and 621. Conductor 626 extends to terminal 1|3, thence over jumper 126, strip 1|1, conductor 806, left winding of relay 800 to battery. Relay 800 will operate over this circuit to identify the No. 0 line choice and extends its operating ground to the winding of relay 8|3 to indicate that the wanted line is to be handled as an individual line. Conductor 621 extends to terminal 1|2, thence over jumper 125 to strip 120, conductor 809, left winding of relay 802 to battery. Relay 802 upon operating identies the No. 0 level and extends its operating ground over its inner left contact to the winding of relay 8|4 to identify the No. 0 frame. It may be noted that relays 6|4 to 8|i represent the four frames of a, choice and are operated from the corresponding energizing circuits for each pair of frame level relays.

With relay 800 operated, the No. 0 line choice is selected by operating the marker preference relay 908 individual to the marker shown in the No. 0 line choice connector. The marker preference relay operates the multicontact relay 909 which extends all of the control circuits from the marker through to the choice. The frame relay 8| 4 closes a circuit from ground through the winding of relay 8|8, contacts of relay 8|4 to the Winding of relay 9|0, which is individual to the No. 0 frame, over equipment (not shown) which determines whether the frame equipment is free to handle a terminating call. Relay 8| 8 operates if the frame equipment is idle and connects ground to the outer left contacts of the level relays 802, 804, etc., and since relay 602 is assumed to be operated, operates horizontal level relay 9| I. Relay 9|| connects the operating circuits for the ten select magnets, corresponding to the ten line junctors which serve the wanted line, through to the marker where one will be selected as described in detail in the Patent No. 2,232,371, granted Feb. 18, 1941 to J. W. Dehn et al. The hold magnet 9| 2 of this line is operated over the front contact of relay 6|9 after an idle channel has been selected.

It will now be assumed that the call was for subscribers line 980 in oilicey unit B and that therefore through the operation of relays 60| and 604 and the same setting of the register relays as previously considered, the number frame 151 is selected by the operation of the frame connector relay 158 and the hundred block relay 159 and the twenty block relay 160 are also operated. It will further be assumed that terminals 16|, 162 and 163 are connected in the manner previously described in connection with terminals 1|I, 1|2 and 1|3, that is terminal 16| is connected over front contacts of relays 160 and 158 and the back contact of relay 6|9 to the winding o! busy test relay 62|, terminal 162 is connected to an armature oi selecting relay 6|9 and terminal 163 is connected over a back contact of relay 6|9 to the winding of relay 623, It will be further assumed that subscribers line 980 where it enters the office unit B is connected to a distributing frame 953 from which the line is extended to one of the primary lin'e switches in accordance with tratc requirements. The

line itself is connected to the line terminals 954 and 955 while individual to the line terminals 954 and 955 are the sleeve or busy terminal 956 and the message register terminal 951.

At the number frame, assuming that the set of number terminals 16|, 162 and 163 represent the number assigned to the line 980, terminal 16| will be cross-connected over jumper 114 to terminal 956 individual to the position in the primary switch 95| assigned to line 980. According to the present disclosure line 980 ap pears in the No. 0 level oi the No. 0 frame in the No. 9 choice and is an individual message rate line. Therefore terminal 162 is connected over jumper 115 to strip '|10 and terminal 163 is connected over jumper 116 to strip 180.

' 'contact of relay 6|9 over contacts of relays 158 and 160 to terminal 163, thence over jumper-116, strip 180, conductor 8|9, left winding of the No. 9 line choice relay 80| to battery. Relay 623 does not operate in this circuit. After an interval to permit theA busy test relays 62|, 622, etc., to operate, ground is connected under the control of the units register to conductor 625, thereby operating relay 6|9 provided relay 62| isr not operated. With relay 6|9 operated, ground is connected to conductors 626 and 621, conductor 626 extending to terminal 163, thence over jumper 116 to strip 180 and conductor 819 through the left winding of relay 80| to battery. The operation of relay 80| over this circuit identies the No. 9 line choice. Relay 80| extends its operating ground to the winding ofj relay 8|3 to indicate that the Wanted line is to be handled as an individual line. Conductor 621 extends to terminal 162, thence over jumper 115 to strip 110, thence over conductor 809, left winding of relay 802 to battery. Relay 802 upon operating identifies the No. level and extends its operating ground over its inner left contact to the winding of relay 8| 4 to identify the No. 0 frame.

With relay 80| operated the No. 9 line choice is selected by operating the marker preference relay 958 individual to the marker shown in the No. 9 line choice connector. The marker preference relay operates the multicontact relay 959 which extends all of the control circuits from the marker through to the choice. The frame relay 8|4 closes a circuit from ground through the winding of relay 8|8, contacts of relay 8|4 to the winding of relay 960, which is individual to the No. 0 frame, over equipment (not shown) which determines Whether the frame equipment is free to handle a terminating call. Relay 8|8 operates if the frame equipment is idle and connects ground to the outer left contacts of the level relays 802, 804, etc., and since relay 802 is assumed to be operated, operates horizontal level relay 96|. Relay 96| connects the operating circuits for the select magnets, corresponding to` the ten junctors which serve the wanted line, through to the marker Where one will be selected. The hold magnet 962 of line 980 is operated over the front contact of relay 6|9 after an idle channel has been selected.

It will now be assumed that the oiilce unit A and the ofce unit/B are reached from the originating oflice over separate trunk groups and that ofc'e unit A is reached over a trunk group including trunks 2|5 and 2|1 terminating in incoming junctors 400 and 40| and that oftlce unit B is reached over a trunk group including trunks 2|6 and 2|8 terminating in incoming junctors 402 and 403. It will be noted that when a trunk of the first group is calling, the group start relay 401 is operated resulting in the operation of trunk group relay 408 and that when a trunk of the second group is calling the group start relay 4|1 is operated resulting in the operation of trunk group relay 4|8. In this case the lower front contacts of relays 408 and 4|8 are patched to ground, the lower armature nf relay 408 is patched over conductor 4|5 to the inner armature of relay 409, the lower armature of relay 4|8 is patched over conductor 4|4 to the next lto inner armature of relay 409, the inner front contact of relay 409 is patched over conductor 4|9 to conductor 504 and the next to inner front contact of relay 409 is patched over conductor 420A to conductor 503. Thus when the sender 500 has been seized and relay 502 thereof has operated, a circuit will be completed over conductor 503 for relay 501 if the call is incoming over the trunk group 2|5, 2|1 for a line terminating in ofllce unit A or a circuit will be completed over conductor 504 for relay 508 if the call is incoming over the trunk group 2|6, 2|8 for a line terminating in oiiice unit B. In terminatingv oces equipped in this manner to identify the called oilice unit by the individual trunk group identification, the upper 'back contacts of relays 501 and 508 would be wired directly to the winding of relay 5|2, the ground connections to the upper cross-points of the incoming group register of the sender would not be wired and the arrow connections in the marker 600 would be connected at th'e point indicated by number 628.

If now a call is incoming for a line in oice unit A and relay 501 is therefore operated, a circuit is established as soon as the sender 500 has been connected to the marker 600 over the marker connector 50|, from batteryt through the winding of relay 60| in the marker, over conductor 602 patched at 628 to conductor 629, contacts of marker connector 50|, upper front contact of relay 501 to checking lead 5| 1. Relay 60| does not, however, operate and consequently relay 603 operates to cause the selection of the number groupof the office unit A as previously described. If, however, the call is incoming for aline in oice unit B and relay 508 is therefore operated, the circuit just traced for relay 60| extends to direct ground at the upper front contact of relay 508 and relays 60| and 603 therefore operate to cause the selection of a number group of the cnice unit B as previously described.

From the foregoing it will be apparent that it is possible in a simple manner to utilize the same terminating equipment for terminating calls in either one of two oice units located in the same oflice building, thereby securing a much more efficient use of such equipment.

What is claimed is:

1. In a telephone system a first oflice, other oilices, switching mechanism in said first ofdce for extending connections to said other omces, a sender in said first oice having Yregisters for registering the office code and numerical designations of wanted lines, means controlled in accordance with the oiilce code registrations for setting said switching mechanism to extend a connection to said other oilices, switching mechanism in said other olces, a sender common to said other ofdces having registers for registering the numerical designations of wanted lines in accordance with the setting of the numerical registers of said first sender, discriminating means in said latter sender operable in accordance with the oilce code registered in said rst' sender 4for determining in which of said other olces a call is to be terminated, and means controlled in accordance with the numerical registrations established in said latter sender and said discriminating means for operating said latter switching mechanism to complete a connection to a wanted line terminating in any of said other ofces.

2. In a telephone exchange system, a ilrst oiiice, other otllces, groups of interofiice trunks extending from said rst oiice to said other oiices, switching mechanism in said first oiiice, a sender in said rst oiiice having registers for registering the oilce code and numerical designations of wanted lines, means controlled in accordance with the ofiice code registrations for setting said switching mechanism to extend a connection to an idle trunk in any of said groups of trunks, switching mechanism in said other ofiices, a sender common to said other oiilces having registers for registering the numerical designations oi wanted lines in accordance with the setting of the numerical registers of said rst senderl discriminating means in said latter sender operable in accordance with the group of trunks in which the seized trunk is located for determining in which of said other oilices a call is to be terminated, and means controlled in accordance with the numerical registrations established in said latter sender and said discriminating means for operating said latter switching mechanism to complete a connection to a wanted line terminating in any of said other omces.

3. In a telephone exchange system, a nrst oilice, other oillces, groups of interofilce trunks extending from said ilrst omce to said other ofiices, switching mechanism in said rst olce, a sender in said rst ofce having registers for registering the oiiice code and numerical designations of wanted lines, means controlled in accordance with the oillce code registrations for setting said switching mechanism to extend a connection to an idle trunk in any of said groups of trunks, switching mechanism in said other oilices, a sender common to said other oiilces having registers for registering the numerical designations of wanted lines in accordance with the setting of the numerical registers of said ilrst sender, means for associating any incoming trunk with said latter sender, relays in said latter sender selectively operable from said associating means in accordance with the group o! trunks in which the seized trunk is located for determining in which of said other olces a call is to be terminated, and means controlled in accordance with the numerical registrations established in said latter sender and the operated one of said relays for operating said latter switching mechanism to complete a connection to a wanted line terminating in any of said other oices.

4. In a telephone exchange system, a rst oilice, other olces, groups of interofdce trunks extending from said first ofiice to said other ofiices, switching mechanism in said iirst ofiice, a sender in said iirst oilice having registers for registering the oiiice code and numerical designations of wanted lines, means controlled in accordance with the office code registrations for setting said switching mechanism to extend a connection to an idle trunk in any of said groups of trunks, switching mechanism in said other oilices, a sender common to said other offices having registers for registering the numerical designations of wanted lines in accordance with the setting oi the numerical registers of said rst sender, means for associating any incoming trunk with said latter sender, relays in said latter sender selectively operable from said associating means in accordance with the group of trunks in which the seized trunk is located for determining in which of said other oiiices a call is to be terminated, a marker associable with said latter sender, transfer means in said marker selectively controlled by said sender relays for determining to which of said other offices said marker shall direct a call, and means in said marker controlled in accordance with the numerical registrations established in said latter sender for operating said latter switching mechanism to complete a connection to a wanted line terminating in the oiIice determined by said transfer means.

5. In a telephone exchange system,'a first oiice, other offices, a common group of trunks extending from said rst olce to said other oilices. switching mechanism in said first office, a sender in said first oiilce having registers i'or registering the oiiice code and numerical designations of wanted lines, means controlled in accordance with the oilice code registrations for setting said switching mechanism to extend a connection to an idle trunk of said group, switching mechanism in said other ofiices. a sender common to said other otiices having registers for registering the numerical designations of wanted lines in accordance with the setting of the numerical registers of said ilrst sender, means controlled in accordance with the omce code registrations of said first sender for establishing a discriminating setting of one of the registers of said latter sender for determining in which of said other oillces a call is to be terminated, and means controlled in accordance with the numerical registrations established in said latter 'sender and the discriminating setting of said one register for operating said latter switching mechanism to complete a connection to a wanted line in any of said other ofilces.

6. In a telephone exchange system, a first ofilce, a second ofllce, a third oilice, a common group of trunks extending from said first oiiice to said other olces, switching mechanism in said iirst oilice, a sender in said ilrst omc'e having registers for registering the omce code and numerical designations of wanted lines, means controlled in accordance with the ofiice code registrations of either said second or third oillces for setting said switching mechanism to extend a connection to an idle trunk of said group, a

sender common to said second and third oilcesl having registers, means for transmitting series of revertive impulses from said latter sender to said iirst sender whereby the registers of said latter sender are set to register the numerical designations of wanted lines in accordance with the setting of the numerical registers of said first sender, means in said first sender operable in accordance with the oiiice code registrations of said third oilce to cause the addition of five impulses to one of said series of revertive impulses to establish a discriminatory setting of one of the registers of said latter sender for determining that a call is to be terminated in said third ofce, and means controlled in accordance with the numerical registrations established in said latter sender and the discriminating setting of said one register for operating said latter switching mechanism to complete a connection to a wanted line in either said second or third office.

vactieve '7. In a telephone exchange system, a first ofiice, other offices, a common group ot trunks extending from said first ofiice to said other oilces, switching mechanism in said first oice, a sender in said first ofce having registers for registering the oiiice code and numerical designations of wanted lines, means controlled in accordance with the ofiice code registrations for setting said switching mechanism to extend a connection to an idle trunk of said group, switching mechanism in said other oilices, a sender common to said other oces having registers for registering the numerical designations of wanted lines in accordance with the setting of the numerical registers of said first sender, means controlled in accordance with the oihce code registrations of said iirst sender for establishing a discriminating setting of one of the registers of said latter sender for determining in which of said omces a call is to be terminated, a marker associable with said latter sender. transfer means in said marked selectably controlled in accordance with the discriminating setting of said one register for determining to which of said other oiiices said marker shall direct a call and means in said marker controlled in accordance with the numerical registrations established in said latter sender to complete a connection to a wanted line terminating in the oilce determined by said transfer means.

8. In a telephone exchange system, a rst oitlce, other oilices. switching mechanism ln said first oiiice for extending connections to said other oices. a sender in said rst omce having registers for registering the oiiice code and numerical designations oi.' wanted lines, means controlled in accordance with the oiiice code resistrations for setting said switching mechanism to extend a connection to said other oiiices, switching mechanism in said other oflices common thereto, a sender common to said'other oiiices having registers for registering the nu. merical designations of wanted lines in accordance with the setting of the numerical registers of said first sender, discriminating means in said latter sender operable in accordance with the ofiice code designations registered in said mst sender for determining in which of said other oiilces a call is to be terminated, and means common to said other oiiices controlled in accordance with the numerical registrations established in said latter sender and said discriminating means for operating said common switching mechanism to complete a connection to a wanted line in any of said other offices.

9. In a telephone exchange system, a rst ofnce, other ofces. groups oi inter oiiice trunks extending from said first office to said other oces,l switching mechanism in said rst oiiice, a sender in said ilrst oiiice having registers for registering the ofiice code and numerical designations of wanted lines. means controlled in accordance with the oflce code registration for setting said switching mechanism to extend a connection to an idle trunk in any of said groups of trunks, switching mechanism in said other oiilces common thereto. a sender common to said other oiilces having registers for registering the numerical designations of wanted lines in accordance with the setting of the numerical registers of said rst sender. discriminating-means in said latter sender operable in accordance with the group ot trunks in which the seized trunk is located for determining in which of said other oinces the call is to be terminated, and means controlled in accordance with the numerical registrations established in said latter sender and said discriminating means for operating said common switching mechanism to complete a connection to a wanted line terminating in any of said other oilices.

10. In a telephone exchange system. a nrst oiiice, other ofiices. means for establishing a connection from said first oiiice to said other oilices, a plurality of subscribers lines terminat-4 lng in each oi.' said other cnices. a plurality of switches common to said other omces in which said lines appear, control equipment common to said lines and to said switches, a cross-connecting rack allocated to each oisaid other ofnces, means to register the directory numbexnof any line and to indicate the particular one ot said a ofces in which the wanted line terminates in said control equipment, means responsive to said oiilce indication to select the cross-connecting rack of the desired omce, means responsive to the directory number registration to select a set oi' terminals on said selected rack individual to said number, means to individualize said set of terminals to a subscribers line, means including said set or terminals to transmit to said control equipment information characteristic of the nature and location of the wanted line, and means responsive to the transmission of said information to connect said control equipment with the switch in which said line appears and for controlling the completion of the connection to said line.

RALPH E. HERSEY. O'I'IMAR H. KOPP. OSCAR MYERS. JAMES B. NEWSOM. 

